Pavement creation and preservation is a technology which has a long history, but only recently have new demands and constraints forced widespread changes in this industry. Environmental protection pressures have eliminated many otherwise tried-and-true materials and solvents for use as pavement constituents. At the same time, roads and other paved surfaces are experiencing the stresses of greater traffic and larger, heavier vehicles and the paving industry must therefore meet commensurately higher paving quality specifications with new, environmentally acceptable materials--and still do so in a commercially competitive way.
One way to preserve the integrity of paved surfaces is to maintain them, so as to avoid the necessity of rebuilding or resurfacing them. A bituminous pavement rejuvenator for such a purpose is disclosed in U.S. Pat. No. 3,221,615, incorporated herein by reference, which is a coal tar derivative composition containing specific ingredients and having particular specifications. Other pavement treating compositions are disclosed in U.S. Pat. Nos. 3,261,269 and 4,661,378, also incorporated herein by reference, which disclose pavement dressing conditioners which contain the above-described bituminous pavement rejuvenator together with additional ingredients and/or solvents. These pavement treating compositions are generally spread or sprayed onto existing pavement surfaces (not only bituminous surfaces but concrete and other surfaces as well) to preserve and to restore the integrity of the pavement.
Even these pavement preserving and restoring compositions, however, do not meet all the needs of the current pavement maintenance industry. They do not generally permeate the surface to be treated fast enough, or at least cannot be relied upon to stay in place despite stresses such as flowing water (from land or air) or restored vehicular traffic. Existing pavement treating compositions are not noted, either, for their ability reliably to fill cracks in bituminous pavement or to yield long wear in such repairs.
Also, an important environmental innovation is the substitution of water for organic solvents as a large component of pavement treating materials. This obvious goal is difficult to meet, however, due to the apparent water insolubility of paving materials generally.
Therefore, a need remains for a composition which can be used to maintain--or to repair--pavement, which has all the advantages of prior art conditioners and rejuvenators but can also be prepared using aqueous or aqueous-based solvents. Such a composition should provide long lasting pavement crack repair, give good resistance to weather soon or immediately after application, and allow for prompt restoration of the pavement to its normal use.